Non-Depolarizing NMBA Effects

Question 1

ND-NMBA MOA

Answer 1

A nondepolarizing neuromuscular blocker (NDNB) circulates to all tissues, including skeletal muscle.

The nondepolarizing neuromuscular relaxant diffuses from the vascular compartment into the synaptic cleft of the neuromuscular junction.

The nondepolarizing agent combines with the nicotinic receptors of the channels of the motor end-plate.

The nondepolarizing agent has no direct effect on the channel.

The nondepolarizing agent, however, competitively blocks acetylcholine from attaching to its receptors so the channel cannot open.

The channel stays closed, and the postsynaptic membrane remains polarized. Thus, a nondepolarizing neuromuscular blockade is established.

Question 2

ND-NMBA Unique Characteristics

Answer 2

Quarternary ammonium compounds

Steroids or benzoisoquinolines

Do not depolarize membrane

Reversible

Do not trigger MH

Question 3

ND-NMBA CV Effects

Answer 3

Atracurium and mivacurium cause histamine release and may produce hypotension and tachycardia.

Pancuronium is vagolytic and causes slight catecholamine release (indirect sympathomimetic), producing tachycardia.

Question 4

ND-NMBA Hepatic and Renal Effects

Answer 4

The steroidal relaxants rocuronium, vecuronium, and pancuronium depend to varying degrees on renal and hepatic elimination

Question 5

ND-NMBA Allergy Considerations

Answer 5

Neuromuscular blocking agents and antibiotics are the most common drugs involved in intraoperative allergic reactions

The initial diagnosis is presumptive, whereas the etiological assessment is linked to the clinical presentation, tryptase levels, and skin test results.

Anaphylaxis presents with significant hypovolemia and vasoplegia,

Aggressive fluid therapy and epinephrine are the cornerstones of management.

Question 6

ND-NMBA Temperature Effects

Answer 6

Hypothermic patients exhibit a prolonged duration of action to all muscle relaxants.

Question 7

Things that prolong ND-NMBA Effects

Answer 7

Volatiles [des > sevo > iso], not clinically significant

Hypothermia: 10-15% ↓ for every degree below 36 ▪ Most with cis and atrac due to
Hofmann (colder = slower)

Magnesium ▪ Opposite of calcium

Lithium

IV local anesthetic ▪ If on drip, check dosing!

Question 8

Things that shorten ND-NMBA Effects

Answer 8

Long term anti-epileptics – resistant to NMB

Steroids antagonize NMB